- What makes a behaviour “abnormal”: the four Ds, and the two rival views of abnormality
- How abnormal behaviour has been explained across history, and by today’s biological, psychological and socio-cultural models
- How psychological disorders are officially classified (DSM-5, ICD-10)
- The symptoms and features of all twelve major categories of psychological disorders in this chapter
- Suicide: risk factors, warning signs and prevention, handled sensitively
diathesis-stress modelanxiety disordersschizophrenianeurodevelopmental disorders
dissociative disorderssubstance-related disorders
This chapter is Unit IV (Psychological Disorders) of the CBSE 2026-27 curriculum, worth 12 of the 70 theory marks.
Class 12 Psychology also has a 30-mark Practical component (a case profile file,
five psychological tests administered and interpreted, and a viva voce): that is
assessed separately and is not part of this notes chapter.
1Introduction
Every one of us faces problems at some point in life: before an exam, worrying
about a career, or when someone close to us is unwell. Most people cope and move
on. But some people react to life’s problems and stresses in an extreme way, and
this is where psychology’s study of abnormal behaviour begins.
Adaptation is a person’s ability to modify their behaviour in response to
changing environmental requirements. When behaviour cannot be modified according
to the needs of a situation, it is called maladaptive.
Abnormal psychology is the area within psychology focused on maladaptive
behaviour: its causes, consequences, and treatment.
The study of psychological disorders has intrigued and mystified all
cultures for more than 2,500 years.
from the chapter’s Introduction
“How can I be substantial without casting a shadow? I must have a dark side,
too, if I am to be whole and by becoming conscious of my shadow, I remember once more that I
am a human being like any other.”
Carl Jung, quoted in the chapter’s Introduction
- Handle this topic sensitively. Do not draw any definite conclusion that you or
someone else has a disorder on the basis of some signs or symptoms you notice. - Mere knowledge and information about psychological disorders do not give the
skills needed to diagnose or treat them. - Do not try to treat each other: specialised training in clinical
psychology/counselling is needed for psychodiagnostic testing.
2Concepts of Abnormality and Psychological Disorders
No single definition of abnormality has won universal acceptance. But most
definitions share four common features, often called the “four Ds.”
Deviance
Different, extreme, unusual, even bizarre
Distress
Unpleasant and upsetting to the person and to others
Dysfunction
Interferes with carrying out daily activities constructively
Danger
Possibly dangerous to the person or to others
Write all four Ds with the book’s one-line meaning for each: deviant, distressing,
dysfunctional and dangerous.
Since “abnormal” literally means “away from the normal,” it implies deviation
from some norm or standard: but psychology has no single “ideal” or “normal
model” of behaviour to compare against. Two basic, conflicting views have emerged:
View 1: Deviation from Social Norms
- Abnormal = behaviour, thoughts and emotions that differ markedly from a society’s ideas of proper functioning
- Norms grow from a society’s own culture, history, values, institutions
- A culture valuing competition may accept aggression; one valuing cooperation (like India) may call the same behaviour abnormal
- Problem: it assumes that socially accepted behaviour is not abnormal, and that normality is nothing more than conformity to social norms
View 2: Maladaptive Behaviour
- Best criterion is not social acceptance but whether the behaviour fosters the well-being of the individual and the group
- Well-being = not just survival but growth and fulfilment (actualisation of potential, as in Maslow’s need hierarchy)
- Even conforming behaviour can be abnormal if it is maladaptive: e.g. a student who stays silent in class despite having questions
3Historical Background
Three explanations for abnormal behaviour keep recurring across the history of
Western civilisation: the supernatural, the biological/organic, and
the psychological perspective.
Do not mix up the four humours (Galen: blood, black bile, yellow bile, phlegm)
with the Indian tridosha (vata, pitta, kapha). The book presents them as similar
concepts from two different traditions, not the same three/four items.
4Classification of Psychological Disorders
A classification is a list of categories of disorders grouped by shared
characteristics. It lets psychologists, psychiatrists and social workers
communicate about disorders, and helps in understanding their causes and the
processes involved in their development and maintenance.
DSM-5
- Published by the American Psychiatric Association (APA)
- Full name: Diagnostic and Statistical Manual of Mental Disorders, 5th Edition
- Gives a specific checklist of clinical signs that must be present, or absent, to diagnose each disorder
ICD-10
- Published by the World Health Organisation (WHO)
- Full name: ICD-10 Classification of Behavioural and Mental Disorders (10th revision of the International Classification of Diseases)
- Officially used in India and elsewhere; gives clinical features and diagnostic guidelines per disorder
5Factors Underlying Abnormal Behaviour
Different approaches emphasise different factors: biological, psychological
and interpersonal, and socio-cultural.
5.1 Biological Factors
Faulty genes, endocrine imbalances, malnutrition and injuries can interfere
with normal development and functioning. The biological model holds that
abnormal behaviour has a biochemical or physiological basis: often a problem in
how neurotransmitters carry messages across the synapse between neurons.
| Neurotransmitter | Abnormal activity | Linked disorder |
|---|---|---|
| GABA (gamma aminobutyric acid) | Low activity | Anxiety disorders |
| Dopamine | Excess activity | Schizophrenia |
| Serotonin | Low activity | Depression |
Remember this table as “GABA down = anxiety, dopamine up = schizophrenia,
serotonin down = depression.”
Genetic factors are linked to bipolar and related disorders, schizophrenia and
intellectual disability, but researchers have not been able to identify the
specific genes that are the culprits. It appears that in most cases, no
single gene is responsible for a particular behaviour or a psychological
disorder: many genes combine, and biology alone cannot account for most
psychological disorders.
5.2 Psychological Models
The psychodynamic model (the oldest and most famous psychological
model, first formulated by Freud) holds that behaviour, normal or abnormal,
is determined by unconscious psychological forces within the person, which
interact with one another. Abnormal symptoms result from conflict between
three central forces: id (instinctual needs, drives, impulses),
ego (rational thinking) and superego (moral standards).
Freud held that abnormal behaviour is a symbolic expression of unconscious
mental conflicts that can be generally traced to early childhood or infancy.
The behavioural model states that both normal and abnormal behaviours
are learned, and psychological disorders result from learning maladaptive
ways of behaving: so what has been learned can also be unlearned.
The cognitive model holds that abnormal functioning can result from
cognitive problems: irrational or inaccurate assumptions and attitudes about
oneself, illogical thinking, and overgeneralisation (drawing broad,
negative conclusions from a single insignificant event).
The humanistic-existential model looks at broader aspects of human
existence. Humanists believe people are born with a natural tendency to be
friendly, cooperative and constructive, and are driven to self-actualise.
Existentialists believe we are born completely free to decide what our own
existence means. Someone who avoids making that choice ends up living an
empty, inauthentic, dysfunctional life.
Psychological models also point to psychological and interpersonal
factors as significant contributors to abnormal behaviour:
Maternal deprivation
Separation from the mother, or lack of warmth/stimulation in early years
Faulty parent-child relationships
Rejection, overprotection, over-permissiveness, faulty discipline
Maladaptive family structures
Inadequate or disturbed family; an enmeshed family where members are overinvolved in each other’s activities, thoughts and feelings: children find it hard to become independent
Severe stress
Along with the three family-related factors above, severe stress is itself named as a psychological/interpersonal factor behind abnormal behaviour
5.3 Socio-Cultural Factors
War and violence, group prejudice and discrimination, economic and
employment problems, and rapid social change put stress on most people and can
trigger psychological problems in some. Lack of social support matters too:
people who lack social support are more likely to become, and stay,
depressed.
Socio-cultural theorists also point to societal labels and roles:
when people break social norms, they are called “deviant” or “mentally ill.” The
label sticks, the person is encouraged to act “sick,” and gradually accepts and
plays the sick role.
5.4 The Diathesis-Stress Model
One of the most widely accepted explanations of abnormal behaviour, applied
to disorders including anxiety, depression and schizophrenia.
6Major Psychological Disorders
The chapter groups psychological disorders into twelve major categories,
following the DSM-5.
6.1 Anxiety Disorders
Some anxiety is normal: we feel it while waiting for an examination, a visit
to the dentist or a solo performance. This is normal and expected, and even
motivates us to do our task well. High levels of anxiety that are distressing
and interfere with effective functioning indicate an anxiety disorder.
Anxiety disorders are the most common category of psychological
disorders. Anxiety is a diffuse, vague, very unpleasant feeling of fear
and apprehension, with symptoms such as rapid heart rate, shortness of breath,
diarrhoea, loss of appetite, fainting, dizziness, sweating, sleeplessness,
frequent urination and tremors.
| Disorder | Key features |
|---|---|
| Generalised Anxiety Disorder | Prolonged, vague, unexplained, intense fears not attached to any object; hypervigilance and motor tension |
| Panic Disorder | Recurrent, unpredictable anxiety attacks of intense terror/dread with physical symptoms: breathlessness, palpitations, trembling, dizziness, fear of losing control or dying |
| Specific Phobia | Irrational fears of specific objects, interactions with others, or unfamiliar situations |
| Separation Anxiety Disorder | Extreme distress on separation (or the expectation of separation) from home or an attachment figure |
| Others in this category | Selective Mutism, Substance/Medication-Induced Anxiety Disorder, Anxiety Disorder Due to Another Medical Condition |
Table 4.1: Major Anxiety Disorders and their Symptoms
Phobias: people who have phobias have irrational fears related to
specific objects, people or situations. Phobias often develop gradually or
begin with a generalised anxiety disorder.
Deb felt his heart racing and started sweating while driving; the attacks
increased over months until he was afraid to drive and eventually stopped
leaving his house. The book opens the anxiety disorders with this case without
naming a diagnosis; his attacks match the panic attacks it describes (intense
terror, palpitations, shortness of breath, fear of going crazy or dying).
6.2 Obsessive-Compulsive and Related Disorders
Obsessive behaviour
Inability to stop thinking about a particular idea or topic, often unpleasant or shameful to the person
Compulsive behaviour
The need to perform certain behaviours over and over: commonly counting, ordering, checking, touching, washing
Other disorders in this category: hoarding disorder, trichotillomania
(hair-pulling disorder), and excoriation (skin-picking) disorder.
6.3 Trauma- and Stressor-Related Disorders
Post-Traumatic Stress Disorder (PTSD) follows a natural disaster (e.g.
a tsunami), a terrorist bomb blast, a serious accident, or war. Symptoms vary
but may include recurrent dreams, flashbacks, impaired concentration, and
emotional numbing. Also included here: Adjustment Disorders and
Acute Stress Disorder.
6.4 Somatic Symptom and Related Disorders
Physical symptoms occur without a physical disease: the person’s
psychological difficulties are expressed as physical complaints with no
biological cause.
| Disorder | Key feature |
|---|---|
| Somatic Symptom Disorder | Persistent body-related symptoms; overly preoccupied with them; frequent doctor visits; significant distress in daily life |
| Illness Anxiety Disorder | Persistent worry about developing a serious illness: the anxiety itself is the main concern, not the physical complaint |
| Conversion Disorder | Reported loss/impairment of a body function (paralysis, blindness, deafness, difficulty walking) with no physical cause, often after a stressful experience |
6.5 Dissociative Disorders
Dissociation is the severance of connections between ideas and
emotions: feelings of unreality, estrangement, depersonalisation, and
sometimes a loss or shift of identity. A sudden, temporary alteration of
consciousness that blots out painful experiences is a defining characteristic
of the dissociative disorders.
| Somatic Symptom & Related | Dissociative |
|---|---|
| Somatic Symptom Disorder: body-related symptoms without (or disproportionate to) a medical condition | Dissociative Amnesia: inability to recall important personal, often stressful, information; forgetting is beyond normal; memory loss with no known organic cause (e.g., head injury) |
| Illness Anxiety Disorder: worry about developing a serious illness | Depersonalisation/Derealisation Disorder: a change in one’s sense of reality and self-perception |
| Conversion: loss of motor/sensory function with no physical cause | Dissociative Identity Disorder: two or more separate, contrasting personalities, generally associated with a history of abuse |
Box 4.1: Salient features of Somatic Symptom & Related Disorders and Dissociative Disorders
Dissociative fugue is part of dissociative amnesia: unexpected travel
away from home/work, taking on a new identity, and inability to recall the old
one; it ends when the person “wakes up” with no memory of the fugue period, and
is often linked to overwhelming stress. Dissociative Identity Disorder
(often called multiple personality) is the most dramatic dissociative disorder,
often associated with traumatic experiences in childhood.
6.6 Depressive Disorders
Depression is one of the most widely prevalent and recognised mental
disorders: it can refer to a symptom or to a disorder. Everyday “feeling
depressed” after a real loss (a break-up, a missed goal) is not the same as the
clinical disorder.
Major Depressive Disorder is a period of depressed mood and/or loss of
interest or pleasure in most activities, together with symptoms such as change
in body weight, sleep problems, tiredness, inability to think clearly,
agitation, greatly slowed behaviour, excessive guilt or worthlessness, and
thoughts of death and suicide.
Genetic make-up
Heredity is an important risk factor for major depression and other depressive disorders
Age
Women more at risk in young adulthood; men more at risk in early middle age
Gender
Women are more likely than men to report a depressive disorder
Life events & support
Negative life events and lack of social support both raise risk
Discuss this topic factually and without sensationalism. Every suicide is a
misfortune. Suicide takes place throughout the lifespan. It is a result of a
complex interface of biological, genetic, psychological, sociological, cultural
and environmental factors. A previous suicide
attempt is the strongest risk factor. Other risk factors: having a mental disorder
(especially depression and alcohol-use disorders), natural disasters, violence,
abuse or loss, and isolation at any life stage.
Suicidal behaviour often reflects difficulty in problem-solving, stress
management and emotional expression; thoughts turn into action when acting on
them seems the “only way out” of a person’s difficulties. These thoughts are
heightened under acute emotional and other distress. The ramifications of
suicide on the social circle and communities tend to be devastating and
long-lasting. The stigma surrounding suicide continues, and because of it many
people who are contemplating or even attempting suicide do not seek help, so
improving identification, referral and management of behaviour is crucial for
preventing suicide. Suicides are
preventable, but this needs government, media and civil society all
working together, not any one of them acting alone.
Limiting access to the means of suicide · Responsible media reporting of
suicide · Alcohol-related policies · Early identification, treatment and care
of people at risk · Training health workers in assessment and management ·
Care and community support for people who attempted suicide.
Any unexpected or striking change affecting an adolescent’s performance,
attendance or behaviour should be taken seriously, such as the signs below.
Identifying Students in Distress
- Lack of interest in common activities
- Declining grades
- Decreasing effort
- Misbehaviour in the classroom
- Mysterious or repeated absence
- Smoking, drinking or drug misuse
Strengthening Students’ Self-Esteem
- Highlight positive life experiences to help build a positive identity
- Provide opportunities to develop physical, social and vocational skills
- Establish trustful communication
- Set goals that are specific, measurable, achievable, relevant, and time-bound
6.7 Bipolar and Related Disorders
Bipolar I Disorder involves both mania and depression, present
alternately and sometimes interrupted by periods of normal mood; manic
episodes rarely appear alone: they usually alternate with depression. Bipolar
mood disorders were earlier called manic-depressive disorders. Types
include Bipolar I Disorder, Bipolar II Disorder, and Cyclothymic
Disorder.
6.8 Schizophrenia Spectrum and Other Psychotic Disorders
Schizophrenia is a descriptive term for a group of psychotic
disorders in which personal, social and occupational functioning deteriorate
due to disturbed thought processes, strange perceptions, unusual emotional
states and motor abnormalities: a debilitating disorder with heavy costs to
patients, families and society.
| Type of delusion | What the person believes |
|---|---|
| Persecution (most common) | Being plotted against, spied on, slandered, threatened, attacked or victimised |
| Reference | Others’ actions or ordinary objects/events carry a special, personal meaning |
| Grandeur | Being a specially empowered person |
| Control | Own feelings, thoughts and actions are controlled by others |
A delusion is a false belief that is firmly held on inadequate
grounds; it is not affected by rational argument and has no basis in reality.
People with schizophrenia may also show formal thought disorders,
namely loosening of associations/derailment (rapidly shifting topics), neologisms
(inventing new words/phrases), and perseveration (repeating the same thought
inappropriately), and hallucinations (perceptions without an external
stimulus): auditory (most common: voices speaking directly to the
patient, “second-person,” or talking about the patient, “third-person”),
plus tactile, somatic, visual, gustatory, and olfactory
hallucinations. Inappropriate affect means emotions unsuited to the
situation.
Negative symptoms include alogia (poverty of speech),
blunted affect (reduced range of emotion) or flat affect (no
emotion shown at all), avolition (apathy, inability to start or
complete tasks) and social withdrawal as a separate, fourth negative
symptom. Psychomotor symptoms can reach the
extreme of catatonia: catatonic stupor (motionless and silent for
long periods), catatonic rigidity (a rigid, upright posture held for
hours), and catatonic posturing (bizarre positions held for long
periods).
6.9 Neurodevelopmental Disorders
These disorders share one feature: they manifest early in development,
often before school or in the early school years, hampering personal, social,
academic and occupational functioning: as deficits/excesses in a behaviour, or
delays in reaching age-appropriate behaviour. If not attended to, these disorders
can lead to more serious and chronic disorders as the child moves into
adulthood.
ADHD: Inattention
- Difficulty sustaining mental effort during work or play
- Hard to keep the mind on one thing, or follow instructions
- Doesn’t listen, can’t concentrate, disorganised, easily distracted
- Forgetful; doesn’t finish assignments; quickly bored
ADHD: Hyperactivity-Impulsivity
- Unable to control immediate reactions, or think before acting
- Difficulty waiting turns or delaying gratification
- Constant motion: fidgets, squirms, climbs, runs around aimlessly
- “Driven by a motor”; talks incessantly
Autism Spectrum Disorder is characterised by widespread impairment in
social interaction and communication, and stereotyped patterns of behaviour,
interests and activities: marked difficulty in social interaction and
communication across contexts, a restricted range of interests, and a strong
desire for routine. About 70% of children with Autism Spectrum Disorder
also have intellectual disabilities. Affected children struggle profoundly
to relate to others, cannot initiate social behaviour, and seem unresponsive to
others’ feelings; many never develop speech, and those who do often have
repetitive, unusual speech patterns. Behaviours may include lining up objects
or rocking (self-stimulatory, like hand-flapping) or self-injurious actions
(like head-banging).
Intellectual disability refers to below-average intellectual
functioning (an IQ of approximately 70 or below) together with deficits
in adaptive behaviour: communication, self-care, home living, social skills,
functional academics, work: that appear before the age of 18.
| Functioning area | Mild (IQ 55 to ~70) | Moderate (IQ 35/40 to ~50/55) | Severe / Profound (IQ below ~35/40, down to below 20/25) |
|---|---|---|---|
| Self-help | Feeds/dresses self, manages own toilet needs | Needs training but can learn adequate self-help skills | No skills to partial skills, but some can care for personal needs on a limited basis |
| Speech/Communication | Adequate receptive & expressive language | Adequate but with speech problems | Receptive language limited; expressive language poor |
| Academics | Grade 3 to 6 with optimal learning environment | Very limited; Grade 1 to 2 maximum | No academic skills |
| Social skills | Has friends; adjusts quickly | Can make friends, but struggles in many situations | Not capable of real friendships/social interaction |
| Vocational | Can hold a job; competitive to semi-competitive; primarily unskilled work | Sheltered work; needs consistent supervision | Generally no employment; needs constant care |
| Adult life | Usually marries, has children; needs help under stress | Usually does not marry or have children; dependent | No marriage/children; always dependent |
Table 4.2: Characteristics of Individuals with Different Levels of Intellectual Disability
Specific Learning Disorder shows up as difficulty perceiving or
processing information efficiently and accurately; it manifests in the early
school years as problems in the basic skills of reading, writing and/or
mathematics. The affected child performs below average for their age, but can
reach an acceptable level with additional input and effort.
6.10 Disruptive, Impulse-Control and Conduct Disorders
Oppositional Defiant Disorder (ODD) shows age-inappropriate
stubbornness: the child is irritable, defiant, disobedient and hostile, but
does not see themself as angry or oppositional, and justifies the behaviour as
a reaction to circumstances. Conduct Disorder and antisocial behaviour
describe age-inappropriate actions that violate family expectations, societal
norms, or the personal/property rights of others: aggression toward people or
animals, non-aggressive property damage, major deceit or theft, and serious
rule violations.
Verbal aggression
Name-calling, swearing
Physical aggression
Hitting, fighting
Hostile aggression
Directed at inflicting injury on others
Proactive aggression
Dominating and bullying others without provocation
6.11 Feeding and Eating Disorders
Of special interest to young people:
| Disorder | Key features |
|---|---|
| Anorexia nervosa | Distorted body image (sees self as overweight); refuses to eat, exercises compulsively, unusual eating habits; can lose large amounts of weight, even starve to death |
| Bulimia nervosa | Eats excessive food, then purges by laxatives, diuretics or vomiting; feels disgusted/ashamed when bingeing, relieved after purging |
| Binge eating | Frequent episodes of out-of-control, faster-than-normal eating; continues till uncomfortably full, even without hunger |
6.12 Substance-Related and Addictive Disorders
Addictive behaviour is one of the most severe problems facing society today,
whether it takes the form of excessive high-calorie eating that leads to
extreme obesity, or the abuse of substances like alcohol or cocaine.
All alcoholic beverages contain ethyl alcohol, absorbed into the blood and
carried to the central nervous system (brain and spinal cord), where it
depresses functioning. It first depresses the brain areas controlling judgment
and inhibition (so people feel talkative, confident, happy); as more is
absorbed, judgment, speech and memory worsen, and people can become emotional,
loud or aggressive; motor difficulties increase: unsteady walking, blurred
vision, hearing trouble, and difficulty driving or solving simple problems.
Alcohol abusers drink large amounts regularly and rely on it to cope; the
body builds tolerance, needing more for the same effect, and produces
withdrawal symptoms on stopping. Alcoholism destroys families, relationships
and careers; intoxicated drivers cause many road accidents; and children of
people with this disorder show higher rates of anxiety, depression, phobias
and substance-related disorders. Excessive drinking can seriously damage
physical health.
Heroin
- Significantly interferes with social and occupational functioning
- Most abusers develop dependence, tolerance, and withdrawal reactions
- Most direct danger: overdose, which slows respiratory centres and can cause death
Cocaine
- Poses serious dangers, with dangerous effects on psychological functioning and physical well-being
- Regular use can lead to intoxication through the day; poor social/work functioning
- Problems in short-term memory and attention
- Dependence develops; stopping brings depression, fatigue, sleep problems, irritability, anxiety
Alcohol · Stimulants (dextroamphetamines, metaamphetamines, cocaine) ·
Caffeine (coffee, tea, caffeinated soda, analgesics, chocolate, cocoa) ·
Cannabis (marijuana/bhang) · Hallucinogens (LSD, mescaline) · Inhalants
(gasoline, glue, paint thinners, spray paints, typewriter correction fluid) ·
Tobacco (cigarettes, bidi) · Opioid (morphine, heroin, cough syrup,
painkillers) · Sedatives/Hypnotics/Anxiolytics (sleeping pills, anti-anxiety
medication).
- Activity 4.1: talk to three people about what they see as abnormal behaviour, and find the common features behind the label.
- Activity 4.2: ‘abnormal’ behaviours that are normal in a situation (talking to yourself while praying; waving your arms as a traffic policeman); list similar examples.
- Activity 4.3: recall your bodily and mental symptoms before the Class X Board examination and rate them mild, moderate or severe.
- Activity 4.4: recall situations (bad news, loss, low marks) that made you sad, and compare your reactions with others’.
- Activity 4.5: identify the type of delusion in five given beliefs.
- Abnormal behaviour = deviant, distressing, dysfunctional and dangerous (the four Ds)
- Two views of abnormality: deviation from social norms vs maladaptive behaviour
- Three historical perspectives: supernatural, biological/organic, psychological: now merged into the bio-psycho-social approach
- Classified by DSM-5 (APA) and ICD-10 (WHO)
- Models: biological, psychodynamic, behavioural, cognitive, humanistic-existential, socio-cultural, diathesis-stress
- GABA↓ = anxiety, dopamine↑ = schizophrenia, serotonin↓ = depression
- Twelve disorder categories: anxiety, OCD-related, trauma/stressor-related, somatic symptom, dissociative, depressive, bipolar, schizophrenia spectrum, neurodevelopmental, disruptive/impulse-control/conduct, feeding and eating, substance-related and addictive
- Suicide: previous attempt is the strongest risk factor; it is preventable with a multi-sectoral approach
- Can I list the four Ds and both views of abnormality without looking?
- Can I name all twelve categories of psychological disorders in order?
- Can I match GABA, dopamine and serotonin to their disorders?
- Can I explain the three components of the diathesis-stress model?
- Can I distinguish positive, negative and psychomotor symptoms of schizophrenia?